The relief or surface configuration of an area. Topographic studies are valuable because they show how lands are developed and give insight into the history and relative age of mountains or plains. Topographic features are developed by physical and chemical processes. Physical processes include the relatively long-term tectonic actions and continental movement that lead to subduction of lands in some cases or to the development of high elevation mountains. Earth surface forms are usually altered more quickly by the action of water, ice, and wind, leading to the development of deep canyons, leveling of mountains, and filling of valleys. Chemical processes include oxidation, reduction, carbonation, solution, and hydrolysis. These reactions lead to the alteration of organic and mineral materials that also influence the topographic forms of the earth.